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Preparation of a novel method for screeing of cobalt chelators
Moravcová, Monika ; Mladěnka, Přemysl (advisor) ; Karlíčková, Jana (referee)
Charles University Faculty of Pharmacy in Hradec Králové Department of Pharmacology & Toxicology Student: Monika Moravcová Supervisor: Assoc. Prof. Přemysl Mladěnka, Pharm.D., Ph.D. Title of thesis: Preparation of a Novel Method for Screening of Cobalt Chelators Cobalt as a structural part of the vitamin B12 is an essential microelement for living organisms including humans. However, its excess is associated with pathological conditions. Cobalt poisoning can be caused for example by exposure to cobalt metal dust during the production of hard metals or follow the corrosion of metal hip prosthesis. Patients intoxicated by cobalt can develop different manifestations including neurological impairment, hypothyroidism or cardiomyopathy. The aim of this work is to prepare a standardized, rapid, cheap but precise method for the screening of cobalt chelators. For this purpose, spectrophotometric detection using 1-nitroso-2-nafphhol-3,6-disulfonic acid disodium salt as the indicator was used. Firstly, it was found that the addition of cobalt ions led to a clear bathochromic shift of the maximum absorbance of the indicator. The relationship between the absorbance and cobalt concentration was highly linear from 470 to 560 nm at all 4 tested pH conditions (4.5, 5.5, 6.8 and 7.5). The sensitivity of the method...
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Photochemical generation of volatile species of cobalt for analytical atomic spectrometry
Vyhnanovský, Jaromír ; Musil, Stanislav (advisor) ; Nováková, Eliška (referee)
This master's thesis deals with the optimization of conditions for photochemical generation of volatile species of cobalt. Volatile species of cobalt were generated in a flow injection system using a high-efficiency flow through UV generator from formic acid based medium. For detection a high-resolution continuum source atomic absorption spectrometer was used. The volatile species were atomized using a diffusion flame atomizer because of its high robustness. First the optimizations of the parameters affecting the atomization in the diffusion flame and the parameters affecting the transport of the volatile species from the UV generator into the atomizer were carried out (flow rates and composition of the gases, type of a separator, observation height). After that, the optimization of the parameters of the photochemical generation itself was carried out. These were the composition of a reaction medium (concentration of formic acid and formate, type of formate salt) and irradiation time. The possibility of generation of the volatile species from acetic acid based medium was also investigated, but no signal was observed. At chosen optimal conditions of generation the influence of potential interferents was examined, mainly from inorganic acids (HNO3 and HCl) and some transition metals (Fe, Cu and Ni)....
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Cobalt alloys and their weld ability
Herčík, Tomáš ; Mrňa, Libor (referee) ; Sigmund, Marian (advisor)
The bachelor thesis is focused on the evaluation of the current state of use of cobalt and cobalt alloys. Due to its shortage and the growing need for precious metal for the production of Li-on batteries, its price, which is now almost at silver prices, is also rising. Some countries even described it as critical and they have bought it in large quantities. From 2020, it is expected that all cobalt will be reserved for the automotive industry, where the use of cobalt in batteries increases their capacity. It is therefore time to look for ways in which precious metal is economised in existing applications. This also includes welding. Of the existing welding technologies, laser welding looks to be the best. In this case no additional material is needed which reduces the need for cobalt. This technology was verified in the experimental part and evaluated by destructive tests (microhardness, microstructure, macrostructure).
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Leachability of Cu, Ni and Co from alkali-activated matrices
Janíčková, Vlasta ; Kalina, Lukáš (referee) ; Koplík, Jan (advisor)
The work deals with the determination and comparison of leaching of heavy metals from two types of alkali activated systems based on blast furnace slag and high-temperature fly ash. These systems are capable in their structure encapsulate heavy metals, toxic substances or radioactive substances, which can be harmful for the environment. The aim of this work is to prepare a mixture with acceptable mechanical properties. Leachibility from matrix was tested according to ČSN EN 12457–4, followed by analyses Inductively Coupled Plasma Optical Emission Spectroscopy (ICP-OES). Structure of matrix was analysed using Scanning electron microscope (SEM).
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Environmental characteristics of mineral waste from metallurgy
Vítková, Martina ; Ettler, Vojtěch (advisor) ; Bollinger, Jean-Claude (referee) ; Dijkstra, Joris J (referee)
Mineralogical and geochemical characteristics of metallurgical wastes from the Cu-Co smelters situated in the Zambian Copperbelt have been investigated. A number of instrumental analytical methods (XRD, SEM/EDS, EPMA, TEM/EDS) has been used to identify primary and secondary phases in smelter slags and dusts. A set of leaching experiments (CEN/TS 14997 pH-static test, EN 12457 batch test) in combination with geochemical modelling has been performed, with the emphasis on the leaching behaviour of potential contaminants and their release as a function of the pH. The effect of sample preparation on metal leachability from slag was also evaluated, considering the grain size reduction required by the standardised leaching protocols. Environmental and health risk assessments of the dust samples have been performed. It was shown that the main carriers of metals in the studied slags were Cu sulphides (bornite, digenite, chalcocite), Co sulphides (cobaltpentlandite), Co-bearing intermetallic phases and alloys. Copper and cobalt were detected in major silicates and spinels, substituting for Fe or Mg in their structures, and in glass. The presence of secondary metal-bearing phases observed on the slag surfaces indicated the reactivity of the slags on contact with water/atmosphere. It was reported that in...
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Structure and Properties of Sintered Tungsten Carbides
Novotná, Hana ; Klakurková, Lenka (referee) ; Čelko, Ladislav (advisor)
This bachelor thesis deals with the structure and properties of sintered tungsten carbides. The literature review section concerns the development of sintered carbides, their composi-tion and structure, different types of carbides, the steps of the production of sintered car-bides, sintering technology and alternative materials for cutting tools. The experimental section deals with composition of WC-Co and is ascertained by the dependency coercivity on WC grain size and also on cobalt content. This work describes the measurement of WC grain size and measurement of the coercivity, one of the fundamental properties of sintered carbides.
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Analysis of locally modified surfaces for selective growth of cobalt
Krajňák, Tomáš ; Bábor, Petr (referee) ; Čechal, Jan (advisor)
In this thesis the chemical composition of silicon substrates locally modified by focused gallium ion beam by X-ray photoelectron spectroscopy is determined. In order to determine the influence of focused ion beam, the sample comprising sputtered square areas with nominal depths in range of 1 to 10 nm was prepared. Next, the sample was heated to elevated temperatures (500 - 700 °C) to reveal changes in the sputtered areas induced by annealing. In this work by X-ray photoelectron spectrometer Kratos Supra and electron microscope Tescan LYRA3 with focused ion beam were used. From the measured spectra of the Si 2p and Ga 2p3/2 peaks measured as a function of nominal sputtering depth and annealing temperature the following main observations were obtained. First, there is the additional peak component in the Si 2p peak, which can be assigned to the amorphous silicon. The second important finding is that gallium can be removed from near surface volume by annealing at temperatures beyond 700 °C.
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Catalytic Activity of Cobalt Impregnated on Ordered Mesoporous Silica Materials in N2O Decomposition.
Kuboňová, L. ; Fridrichová, D. ; Peikertová, P. ; Mamulová Kutláková, K. ; Kozubová, S. ; Jirátová, Květa ; Obalová, L. ; Cool, P.
Three different ordered mesoporous silica materials, such as MCM-41, Al containing MCM-41 (mass ratio Si/Al = 10) and SBA-15, were prepared. In a next step, cobalt (5-8 wt%) as an active metal for redox reactions, was introduced by the impregnation. The prepared catalysts were characterized by AAS, EDX, N-2 physisorption, XRD, DR UV-Vis spectroscopy, Raman spectroscopy, TPR-H-2 and their catalytic properties were evaluated for N2O decomposition and reduction. The catalysts showed poor activity in N2O decomposition while the use of reducing agent (carbon monoxide) was beneficial for their catalytic activities. The lowest catalytic activity showed Co/Al-MCM indicating that the aggregated CoxOy species present in this catalyst were inactive and not beneficial for the catalytic activity.
Fulltext: content.csg -  PDF
Plný tet: NANOCON 2015 - PDF
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